High-tension electric cable



July 15, 1930.

E. W. CLARK HIGH TENSION ELECTRIC CABLE Filed July 16, 1929 Inv e ITEOT:

Ernest- \X/. Clark, MW

Hts Attor ne g Patented July 15, 1930 HIGH-TENSION ELECTRIC CABLE Application filed July 16,

in permeating the insulation.

For a consideration of what I believe to be f novel and my invention attention is directed to the accompanying specifications and the claims appended theretoi Fig. 1 is a view partly in elevation of a piece b of high tension electric cable; Fig. 2 is a perspective view of the strip used in formb ing the oil channel; Fig. 3. is a section taken on line 3-3 of Fig. 1, and Figs. 4 and 5 are modified forms of the strip.

6 indicates an electric conductor which is surrounded by a body of insulation 7 which is commonly made of strips or ribbons of paper and tightly wound thereon, the joints between strips in the various layers over apping. Surrounding the insulation and separated therefrom by a space is a lead'or equivalent iheath 8.

In order to form an oil channel which exends annularly and longitudinally of the table there is tightly and spirally wound ver the insulation a thin metal tape or stri L The strip is provided with a large number f small individual rojections 10, some of which are on the si e of the strip adjacent o the insulation and the others are on the utside of the strip and engage the inner wall f the sheaths. These pro ections both inside nd outside of the strip or tape 9 hold the arts in concentric relation and also form an mnular channel 11 for the oil, said projecons extending radially when the strip is in lace. The oil permeates the insulation and so'eompletely fills the channel. In order insure the complete filling of the channel all times suitable reservoirs may be pro ded at intervals along the length of the N in a manner that is well understood.

1929. Serial No. 378,777.

By providing numerous small projections on the metal strip or ribbon the latter can be smoothly and evenly wound over the insulation and the outer projections afl'ord a good seat for the lead sheath. volutions of the strip may be separated by a small clearance 12 so that the oil can freel enter the paper in the region thereof.

The pro ections on the tape, or strip may be on both sides thereof or only on one side 60 as shown in Figs. 4 and 5. Where the projections are provided on both sides there is ormed what amounts to two concentric oil channels, one between the tape or strip and the insulation and the other between or strip and the inner wall of the sheath as est shown in Fig. 3. .By making the projections numerous and with and indentations, the

made without sharp corners or rough edges 80 of any kind. 7

The construction shown in Fig. 5 is somewhat simpler to make than the constructions p previously described. In this case the strip say of the order of 85 9 is made of thin copper, 5 to mils in thickness and- 1" wide and the projections are spherical in form and and project above the plane of the strip, say of the order off; of an inch. The projections in this case, as well as in the are staggered. By using these well rounded projections it is a simpler operation to wind in the strip or tape than with the other forms as there is less chance of the projections catching during the winding operation. Where the ribbon is made thin,

in .order to reduce. the cost the projections should not extend quite to the edges of the strip, because if they did there would be as it naturally would more likelihood of the edges of the strip tear- The turns or con.

the tape suitable matched rollcase of Fig. 2,

ing while being wound in place under considerable tension. The strips shown in Figs. 4c and 5 may be wound with the projections extending outwardly or inwardly as desired. It is preferable, however, to have the projections on the outer surface thereby, avoiding denting the insulation and at the same time affording a good seat for the sheath.

I claim:

1. In an oil filled electric cable, the combination of a conductor, insulation thereon, an enclosing sheath, and a strip having a lurality of small individual projections t ereon, said strip being located between the insulation and the inner wall of the sheath and defining therewith an annular oil channel.

2. In an oil filled electric cable, the combination of a conductor, insulation thereon, an

enclosing sheath, and a spirally wound metal strip which is supported by the insulation and has a plurality of small outwardly extending projections thereon which engage the inner wall of the sheath and define between it and the body of the strip an annular oil channel.

3. In an oil filled electric cable, the combination of a conductor, permeable insulation thereon, a metal sheath, and a stri of metal which is spirally wound on the insu lation and has a large number of individually formed projections which engage the inner wall of the sheath and support the same and also cooperate with the sheath to define an annularoil channel.

4. In an oil filled electric cable, the combination of a conductor, permeable insulation thereon, a sheath and a strip of metal which is tightly wound over the insulation and under the sheath, and said strip having a large number of small projections on one side thereof and in staggered relation, the projections and inner wall of the sheath defining an annular and longitudinally extending oil channel.

5. In an oil filled electric cable, the combination of a conductor, permeable insulation thereon, a metal sheath, and a thin strip of metal having a large number of individual projections on one side only, said strip being mounted on the insulation with the projections extending outwardly to form a seat for the sheath and-defining therewith an annular oil channel.

In witness whereof, I have hereunto set my hand this 15th day of July, 1929.

" ERNEST W. CLARK. 

